Conventionally, when a sheet-like porous body that is used for a filter, a gas diffusion member, a heat radiation member, a water absorption member, or the like is produced, an expandable slurry including an inorganic powder, a foaming agent, an organic binder, a liquid solvent, or the like is shaped in a sheet, thereafter, the expandable slurry is foamed using a foaming agent, and the expandable slurry that has been foamed is furthermore dried and baked, as described in, for example, Japanese Patent Publication No. 3282497.
When shaping the expandable slurry into a sheet, the expandable slurry is passed between a carrier sheet constituting a belt conveyer and transferring the expandable slurry, and a doctor blade disposed at an upper portion thereof.
Here, an opened chamber accumulating the expandable slurry is disposed at an upstream side of the doctor blade.
An upper portion of the opened chamber is opened in an atmosphere, and the expandable slurry can be provided to the opened chamber.
In the case of shaping the expandable into a sheet as described above, by intermittently or continuously providing the expandable slurry to the opened chamber, it is possible to continuously shape an expandable slurry sheet for a long period of time.
However, the expandable slurry that has been provided to the opened chamber includes air bubbles. Since the upper portion of the opened chamber is opened in an atmosphere, the air bubbles are accumulated by an ascending force at the upper portion of the opened chamber.
Specifically, when continuously shaping the expandable slurry sheet for a long period of time, the size of the air bubbles become large which is caused by joining the air bubbles that have been accumulated at the upper portion.
When the number of air bubbles whose size become large increases, there is a problem in that these air bubbles whose size became large passes between the carrier sheet and the doctor blade.
Consequently, in the expandable slurry sheet that has been shaped so as to include air bubbles whose size became large, since variations in the size of the air bubbles easily occur, there is a problem in that distribution of air bubbles in the porous body becomes uneven.